DESCRIPTION: (From Applicant's Abstract) Because cancer is the second leading cause of death in postmenopausal women, detailed epidemiological investigations are warranted to identify etiologic factors, including potentially modifiable risk factors. The Iowa Women's Health Study (IWHS) recruited a population-based cohort of 41,837 Iowa women, aged 55-69 years in 1986, to determine whether diet, body fat distribution, and other risk factors were related to cancer incidence. Exposure and lifestyle information was collected in a baseline mailed survey and four follow-up surveys. Cancer incidence and mortality have been ascertained since 1986 by linkage with the State Health Registry of Iowa, a SEER site, and the National Death Index. The project has been extremely productive, with more than 90 publications. Because of the existing wealth of information on this large cohort of women, we propose in this 5-year renewal to extend follow-up for cancer incidence and mortality through 18 years. Further IWHS is expected to yield a total of at least 8,150 incident cancers and 11,000 deaths. This will allow us to perform additional analyses in four broad areas to test hypotheses about a) potential risk factors for uncommon cancers not yet studied in this cohort; b)unexamined potential risk factors for incident common cancers; c) risk factors for incident cancers examined in a limited fashion previously; and d) potential contributors to better survival of breast, colorectal, ovarian, or uterine cancer. We also propose to expand our existing nested case-control study of candidate genes for breast cancer to 432 cases and 332 controls. We will genotype polymorphisms in genes affecting estrogen-metabolizing enzymes and DNA repair proteins, to test the hypothesis that these are associated with risk of breast cancer. The proposed project will provide new information on the risk and survival of cancer in older women. Two recent Program Announcements from the National Cancer Institute emphasize the need for risk factor information on older women (PA-98-028 Diet, Lifestyle and Cancer in U.S. Specific Populations) and on survival (PA-98-027 Cancer Survival Studies in Established Epidemiologic Cohorts). The information that the IWHS will provide could be valuable in the control of this major public health problem.